Cooling and heating device

ABSTRACT

[Object] 
     The purpose is to provide a cooling and heating device. 
     [Solution] 
     This cooling and heating device includes: a fuel cell device including a fuel cell; a heating unit which utilizes the heat of exhaust gas discharged from the fuel cell; a thermoacoustic cooler ( 14 ) including a cooling unit which performs a cooling function with use of the heat of the exhaust gas discharged from the fuel cell; and an exhaust gas switching unit ( 25 ) which allows the exhaust gas discharged from the fuel cell to be supplied to at least one of the thermoacoustic cooler ( 14 ) and the heating unit, whereby there can be provided a cooling and heating device which effectively utilizes the exhaust gas of a fuel cell.

TECHNICAL FIELD

The present invention relates to a cooling and heating device thatincludes a combination of a thermoacoustic cooler and a fuel celldevice.

BACKGROUND ART

In recent years, there have been proposed, as next generation energysources, various fuel cell modules that include fuel cells capable ofgenerating power using a fuel gas (hydrogen-containing gas) and anoxygen-containing gas (air) in a housing, and various fuel cell devicesthat include fuel cell modules in an exterior casing (refer to PatentDocument 1, for example).

Further, in recent years, there have been proposed thermoacousticrefrigerators having a refrigerating function based on thermoacousticenergy (refer to Patent Document 2, for example).

CITATION LIST Patent Literature

Patent Document 1: Japanese Unexamined Patent Application PublicationNo. 2007-59377A

Patent Document 2: Japanese Unexamined Patent Application PublicationNo. 2013-117325A

SUMMARY OF INVENTION Technical Problem

While various devices such as fuel cell devices and thermoacousticrefrigerators have been developed as next generation energy sources asdescribed above, there is still considerable room for investigating thedevelopment of novel applications that combine these devices.

Therefore, an object of the present invention is to provide a novelapplication that combines a thermoacoustic cooler that usesthermoacoustic energy and a fuel cell device.

Solution to Problem

A cooling and heating device of the present invention includes a fuelcell device including a fuel cell; a heating unit configured to utilizethe heat of exhaust gas discharged from the fuel cell; a thermoacousticcooler including a cooling unit configured to perform a cooling functionwith use of the heat of the exhaust gas discharged from the fuel cell;and an exhaust gas switching unit that allows the exhaust gas dischargedfrom the fuel cell to be supplied to at least one of the thermoacousticcooler and the heating unit.

Advantageous Effects of Invention

The cooling and heating device of the present invention switches asupply destination of the exhaust gas discharged from the fuel cell toat least one of the heating unit and the thermoacoustic cooler toselectively utilize one of the heating function of the heating unit andthe cooling function of the cooling unit, thereby making it possible toachieve an efficient cooling and heating device.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a configuration diagram illustrating an example of aconfiguration of a cooling and heating device of an embodiment.

FIG. 2 is a configuration diagram illustrating another example of theconfiguration of the cooling and heating device of the presentembodiment.

FIG. 3 is an exterior perspective view of an example of a fuel cellmodule constituting a fuel cell device of the present embodiment.

FIG. 4 is a cross-sectional view of the fuel cell module illustrated inFIG. 3.

FIG. 5 is a configuration diagram illustrating yet another example ofthe configuration of the cooling and heating device of the presentembodiment.

FIG. 6 is a configuration diagram illustrating yet another example ofthe configuration of the cooling and heating device of the presentembodiment.

DESCRIPTION OF EMBODIMENTS

FIG. 1 is a configuration diagram illustrating an example of aconfiguration of the cooling and heating device of the presentembodiment, FIG. 2 is a configuration diagram illustrating anotherexample of the configuration of the cooling and heating device of thepresent embodiment, FIG. 3 is an exterior perspective view of an exampleof the fuel cell module illustrated in FIGS. 1 and 2, and FIG. 4 is across-sectional view of the fuel cell module illustrated in FIG. 3. Notethat FIG. 1 illustrates a cooling function, FIG. 2 illustrates a heatingfunction, and the configuration of each device is the same. Thus, in thefollowing descriptions of the configurations, FIG. 1 will be mainly usedfor explanation.

The cooling and heating device illustrated in FIG. 1 includes a powergenerating unit as an example of a fuel cell device, and athermoacoustic cooler that produces thermoacoustic energy using exhaustgas discharged from the power generating unit and performs cooling(refrigeration) using the produced thermoacoustic energy. Note that inthe subsequent figures, the same reference numerals are used for thesame components.

The power generating unit as the fuel cell device illustrated in FIG. 1includes a cell stack 2 that includes a plurality of fuel cells, a rawfuel supplying means 4 for supplying a raw fuel such as a city gas, anoxygen-containing gas supplying means 5 for supplying anoxygen-containing gas to the fuel cells constituting the cell stack 2,and a reformer 3 that performs steam reforming on the raw fuel usingsteam. Note that, while described later, a fuel cell module 1(hereinafter, may be abbreviated as “module 1”) includes the cell stack2 and the reformer 3 in a housing. In FIG. 1, the module 1 is surroundedby a long dashed double-short dashed line. Further, while notillustrated in the figures, an ignition device for combusting the fuelgas not used in power generation is provided in the module 1.

The power generating unit illustrated in FIG. 1 includes a heatexchanger 6 that subjects exhaust gas (exhaust heat) to heat exchange todecrease the temperature of the exhaust gas, the exhaust gas beinggenerated through the power generation in the fuel cells that constitutethe cell stack 2. In the present embodiment, while described in detaillater, the heat exchanger 6 functions as a heating unit, and thereforethe heating unit is described as the heat exchanger 6 in the followingdescriptions. Note that the heat exchanger 6 includes a condensed watertreatment device 7 for turning condensed water obtained by thecondensation of moisture contained in the exhaust gas into pure water,and a water tank 8 for storing the water (pure water) treated by thecondensed water treatment device 7. The water tank 8 and the heatexchanger 6 are connected through a condensed water supply pipe 9.Further, depending on the quality of the condensed water generated byheat exchange in the heat exchanger 6, the condensed water treatmentdevice 7 may not be provided. Furthermore, when the condensed watertreatment device 7 is capable of storing water, the water tank 8 may notbe provided.

The water stored in the water tank 8 is supplied to the reformer 3 by awater pump 11 provided in a water supply pipe 10 that connects the watertank 8 and the reformer 3.

Furthermore, the power generating unit illustrated in FIG. 1 includes asupply power regulating unit (power conditioner) 12 that converts DCpower generated in the module 1 into AC power and regulates the amountof converted electricity to be supplied to an external load, and acontroller 13 that controls the operation of various devices. Each ofthese devices constituting the power generating unit is housed in anexterior casing, which forms a simple fuel cell device that can beeasily installed.

The following describes a thermoacoustic cooler 14. The thermoacousticcooler 14 includes a prime mover 15, a cooler 16, and a connecting pipe17 that connects the prime mover 15 and the cooler 16. Note that theprime mover 15, the cooler 16, and the connecting pipe 17 are filledwith a gas such as a helium gas. Further, heat accumulators 18, 19 arerespectively disposed in the prime mover 15 and the cooler 16. One sideof the heat accumulator 18 of the prime mover 15 serves as ahigh-temperature portion 22 (upper side in FIG. 1) while the other sideserves as a low-temperature portion 20 (lower side in FIG. 1).Thermoacoustic energy (sound waves) is produced by the temperaturegradient between the two.

In FIG. 1, although described later, the prime mover 15 is configured toallow the exhaust gas discharged from the module 1 to flow around thehigh-temperature portion 22 of the heat accumulator 18. While, on theother hand, nothing is provided around the low-temperature portion 20 inFIG. 1, in order to produce thermoacoustic energy more efficiently, theprime mover 15 may be configured to allow a low-temperature refrigerant(such as tap water) to flow around the low-temperature portion 20. Thehigh-temperature portion 22, the low-temperature portion 20, and theheat accumulator 18 form a thermoacoustic energy producing unit. Thisthermoacoustic energy producing unit is indicated by the dashed line inFIG. 1.

The thermoacoustic energy produced in the thermoacoustic energyproducing unit resonates upon flowing through the prime mover 15 and theconnecting pipe 17, and is transmitted to the cooler 16. In the cooler16, the thermoacoustic energy is converted into thermal energy. Then, afluid is made to flow to a high-temperature portion 23 (upper side inFIG. 1) on one side of the heat accumulator 19. This causes anendothermic reaction to occur in a low-temperature portion 21 (lowerside in FIG. 1) on the other side of the heat accumulator 19, anddecreases the temperature. As a result, a cooling function is impartedto the cooler 16. That is, the heat accumulator 19, the high-temperatureportion 23, and the low-temperature portion 21 form a cooling unit. Thiscooling unit is indicated by the dashed line in FIG. 1.

Note that, in the cooling unit, the high-temperature portion 23 onlyneeds to be higher in temperature than the low-temperature portion 21,and not high in temperature in the general sense. Specifically,decreasing the temperature of the high-temperature portion 23 decreasesthe temperature of the low-temperature portion 21 even further, therebyimparting a cooling function as well as a refrigerating function to thecooling unit. In other words, the cooling unit has the function as arefrigerating unit. Thus, while in FIG. 1 a second piping 24 describedlater is provided so that a second fluid that flows through this secondpiping 24 flows around the low-temperature portion 21 and then flowsaround the high-temperature portion 23, the second piping 24 need notnecessarily be provided around the high-temperature portion 23.

Further, an exhaust gas switching unit 25 is provided for allowing theexhaust gas discharged from the module 1 to flow into at least one ofthe heat exchanger 6 and the thermoacoustic cooler 14. The provision ofthe exhaust gas switching unit 25 makes it possible to allow the exhaustgas to suitably flow into the heat exchanger 6 or the thermoacousticcooler 14 as needed, and thus provide a heating effect and a coolingeffect.

Thus, during hot periods such as summer, it is possible to make theexhaust gas discharged from the module 1 flow into the thermoacousticcooler 14, and then utilize the second fluid cooled by the cooling unit21 to provide a cooling function. Further, during cold periods such aswinter, it is possible to make the exhaust gas discharged from themodule 1 flow into the heat exchanger 6, and then utilize the firstfluid heated by the heat exchanger 6 to provide a heating function. Thismakes it possible to provide an efficient cooling and heating device.

Note that while FIGS. 1 and 2 illustrate a common house as an example ofa cooling/heating target area, the target area is not limited thereto.The cooling/heating target area is not particularly limited as long asthe area requires air conditioning, such as an architectural structureincluding a building, an aircraft, or a boat or ship.

Furthermore, FIGS. 1 and 2 illustrate an example in which circulationpiping 26 is provided under the floor of this cooling/heating targetarea, and first piping 30 through which the first fluid flows, and thesecond piping 24 through which the second fluid flows are connected tothis circulation piping 26. The first piping 30 is connected to the heatexchanger 6 and the second piping 24 is provided around the coolingunit. Note that one end of the first piping 30 and one end of the secondpiping 24 are connected to the circulation piping 26 via a firstswitching unit 27, and the other end of the first piping 30 and theother end of the second piping 24 are connected to the circulationpiping 26 via a second switching unit 28. Thus, the controller 13 allowsthe first fluid or the second fluid to flow through the circulationpiping 26 by controlling the first switching unit 27 and the secondswitching unit 28, making it possible to effectively function as acooling and heating device.

However, because it is only necessary to provide a cooling and heatingfunction in the cooling/heating target area, the first piping 30 and thesecond piping 24 may each have a circulation piping function asindividual piping or, for example, may each be provided with an open endstructure so that the first fluid that flows through the first piping 30and the second fluid that flows through the second piping 24, or the airor the like heated and cooled by these fluids, are directly supplied tothe cooling/heating target area. In this case, the circulation piping isnot required. Incidentally, in this case, a blower is preferablyattached to one end side of each piping to supply air to the firstpiping 30 and the second piping 24.

The following describes an operation method of the cooling and heatingdevice illustrated in FIGS. 1 and 2. At startup of the fuel cell device,the controller 13 activates the raw fuel supplying means 4, theoxygen-containing gas supplying means 5, the water pump 11, and theignition device. At this time, the temperature of the module 1 is low,and thus power is not generated in the fuel cells and a reformationreaction is not performed in the reformer 3. The fuel gas supplied bythe raw fuel supplying means 4 that has not been used in powergeneration is combusted almost in its entirety, and the combustion heatincreases the temperatures of the module 1 and the reformer 3. When thetemperature of the reformer 3 reaches a temperature that allows steamreforming, the reformer 3 performs steam reforming and a fuel gas whichis a hydrogen-containing gas required for power generation in the fuelcells is produced. Note that, once the reformer 3 reaches a temperaturethat allows steam reforming, the controller 13 may also perform controlso as to activate the water pump 11. When the fuel cells reach atemperature that allows power generation to start, the fuel cells startgenerating power using the fuel gas produced in the reformer 3 and theoxygen-containing gas supplied by the oxygen-containing gas supplyingmeans 5. The electricity generated in the cell stack 2 is converted toAC in the supply power regulating unit 12 and then supplied to anexternal load.

Note that, after power generation has started in the fuel cells, thecontroller 13 controls the operation of the raw fuel supplying means 4,the oxygen-containing gas supplying means 5, the water pump 11, and thelike on the basis of a fuel utilization rate (Uf), an air utilizationrate (Ua), and a steam to carbon (S/C) ratio set in advance in order toefficiently operate the fuel cell device. The S/C is a molar ratio ofthe water and the carbon in the fuel under the steam reforming performedby the reformer 3. The fuel utilization rate is a value obtained bydividing the amount of fuel gas used in power generation by the amountof fuel gas (raw fuel) supplied by the raw fuel supplying means 4, andthe air utilization rate is a value obtained by dividing the amount ofair used in power generation by the amount of air supplied by theoxygen-containing gas supplying means 5.

The exhaust gas produced in association with the operation of the cellstack 2 is made to flow into at least one of the heat exchanger 6 andthe thermoacoustic cooler 14 by the exhaust gas switching unit 25.Whether the exhaust gas is made to flow into the heat exchanger 6 or thethermoacoustic cooler 14 can be set by the user or automaticallyswitched.

For example, a cooling and heating switch is provided in thecooling/heating target area (the switch including shutdown as well) and,when the user switches the switch to utilize cooling or when cooling isautomatically run when a predetermined condition is satisfied, thecontroller 13 controls the exhaust gas switching unit 25 so that atleast a portion (preferably all) of the exhaust gas discharged from themodule 1 flows into the thermoacoustic cooler 14. The exhaust gas thathas flowed toward the thermoacoustic cooler 14 flows through thehigh-temperature portion 22 that constitutes the thermoacoustic energyproducing unit in the prime mover 15 of the thermoacoustic cooler 14.Specifically, piping (a flow path) through which the exhaust gasdischarged from the module 1 flows is provided so as to surround the oneside (high-temperature portion 22) of the piping having the heataccumulator 18 disposed therein. With such a configuration, the exhaustgas flows through the high-temperature portion 22 of the thermoacousticenergy producing unit. Similarly, in the following descriptions, eachpiping is disposed so as to surround the piping of the thermoacousticcooler 14, and configured so that each fluid flows through each area ofthe thermoacoustic cooler 14.

As a result, a temperature gradient is produced between the one side andthe other side of the heat accumulator 18, making it possible togenerate thermoacoustic energy. Note that the low-temperature portion 20as the thermoacoustic energy producing unit can produce thermoacousticenergy more efficiently when the difference in temperature between thelow-temperature portion 20 and the high-temperature portion 22increases, and therefore tap water having a room temperature or the likemay be supplied to the low-temperature portion 20, for example.

In this case, the controller 13 controls the first switching unit 27 andthe second switching unit 28 so that the second fluid (water, air, orthe like) that flows through the second piping 24 flows through thecirculation piping 26. That is, the second fluid that flows through thesecond piping 24 is cooled while flowing through the low-temperatureportion 21 of the cooling unit 20, and the cooled second fluid flowsthrough the circulation piping 26 via the high-temperature portion 23 ofthe cooling unit 20, thereby cooling the cooling/heating target area andproviding a cooling function. Note that the second piping 24 isconfigured to allow the second fluid that has flowed through thelow-temperature portion 21 of the cooling unit to flow through thehigh-temperature portion 23, making it possible to further enhance thecooling function of the cooling unit. Further, the amount (flow rate) ofthe second fluid that flows through the second piping 24 and thecirculation piping 26 can be regulated as appropriate by controlling apump 31 provided between the first switching unit 27 and the secondswitching unit 28.

Further, FIGS. 1 and 2 illustrate an example in which a temperaturesensor 29 is provided in the cooling/heating target area. For example,the controller 13 may perform control so that the first switching unit27 and the second switching unit 28 are automatically switched to allowthe second fluid to flow through the circulation piping 26, when thetemperature sensor 29 satisfies a suitably set first condition (atemperature of at least 25° C. continuing for at least one hour, forexample). Note that while FIGS. 1 and 2 illustrate an example in whichthe temperature sensor 29 is provided in the cooling/heating targetarea, the location in which the temperature sensor 29 is provided is notlimited thereto, and the temperature sensor 29 may be disposed outsidethe cooling/heating target area to measure the temperature of an outsideair.

On the other hand, when the user changes the switch to utilize heatingor when heating is automatically run when a predetermined condition issatisfied, the controller 13 controls the exhaust gas switching unit 25so that at least a portion (preferably all) of the exhaust gasdischarged from the module 1 flows into the heat exchanger 6 serving asthe heating unit. The exhaust gas that has flowed toward the heatexchanger 6 exchange heat with the first fluid (water, air, or the like)that flows through the first piping 30 connected to the heat exchanger6, heating the first fluid.

Then, the controller 13 controls the first switching unit 27 and thesecond switching unit 28 so that the first fluid that flows through thefirst piping 30 flows through the circulation piping 26. That is, thefirst fluid that flows through the first piping 30 is heated whileflowing through the heat exchanger 6, and the heated first fluid flowsthrough the circulation piping 26, thereby heating the cooling/heatingtarget area and providing a heating function. Further, the amount (flowrate) of the first fluid that flows through the first piping 30 and thecirculation piping 26 can be suitably regulated by controlling the pump31 provided between the first switching unit 27 and the second switchingunit 28.

Incidentally, to automatically start the heating function on the basisof the temperature sensor 29 provided in the cooling/heating targetarea, the controller 13 may perform control so that the first switchingunit 27 and the second switching unit 28 are automatically switched toallow the first fluid to flow through the circulation piping 26, whenthe temperature sensor 29 satisfies a suitably set second condition (atemperature of at least 10° C. continuing for at least one hour, forexample).

The adoption of such an operation method as described above results inthe development of a novel application that combines the fuel celldevice and the thermoacoustic cooler 14, making it possible to achievean efficient cooling and heating device.

Note that, for example, when the user turns off the cooling and heatingswitch, or when the temperature measured by the temperature sensor doesnot satisfy the first and second condition (a temperature of at least10° C. and less than 25° C. continuing for at least one hour, forexample), the controller 13 may control the exhaust gas switching unit25 so that the exhaust gas flow as is into the thermoacoustic cooler 14in order to discharge the exhaust gas outside. In this case, thecontroller 13 preferably stops the pump 31 as well. Note that the firstcondition and the second condition may be set as appropriate.

On the other hand, when water for steam reforming in the reformer 3 isto be produced using the heat exchanger 6, the controller 3 can alsocontrol the operation of the exhaust gas switching unit 25 and the pump31 so that condensed water is obtained in amounts as necessary. However,the operation of the pump 31 is preferably suitably controlled so that alarge amount of first fluid does not flow through the circulation piping26.

Incidentally, in the cooling and heating device illustrated in FIGS. 1and 2, solid oxide fuel cells (cell stack 2) are used as the fuel cells,and thus the heat of the exhaust gas discharged from the module 1becomes extremely high in temperature. Using such exhaust gas makes itpossible to efficiently produce the first fluid heated by the heatexchanger 6 and the second fluid cooled by the thermoacoustic cooler 14.

Next, the fuel cell device of the present embodiment will be described.

FIG. 3 is an exterior perspective view of an example of a module in afuel cell device constituting the cooling and heating device of thepresent embodiment, and FIG. 4 is a cross-sectional view of FIG. 3.

The module 1 illustrated in FIG. 3 includes two cell stacks 2 and a cellstack device 40 housed in a housing 34. In each of the cell stacks 2,cylinder-shaped fuel cells 32 are arranged uprightly in a row, eachincluding a fuel gas flow path (not illustrated) through which a fuelgas flows; the fuel cells 32 adjacent to each other are electricallyconnected in series via a current collection member (not illustrated inFIG. 3); and a lower end of each of the fuel cells 32 is fixed to amanifold 33 by an insulative bonding material (not illustrated) such asa glass sealing material. In the cell stack device 40, the reformers 3for producing a fuel gas to be supplied to the fuel cells 32 aredisposed above each of the cell stacks 2. At both end portions of eachof the cell stacks 2, there is disposed an electrically conductivemember that includes an electricity drawing unit for collectingelectricity generated by the power generation in the cell stack 2 (thefuel cells 32) and drawing the electricity to the outside (notillustrated). The cell stack device 40 is thus configured with each ofthe members described above. Note that FIG. 3 illustrates an example inwhich the cell stack device 40 includes two cell stacks 2. However, thenumber of cell stacks may be changed as appropriate; for example, thecell stack device 40 may include only one cell stack 2.

Further, the examples of the fuel cells 32 illustrated in FIG. 3 arehollow flat plate-shaped fuel cells that each include a fuel gas paththat allows fuel gas to flow through the fuel cells in the lengthwisedirection thereof. The fuel cells 32 are solid oxide fuel cells thateach include a fuel electrode layer, a solid electrolyte layer, and anoxygen electrode layer stacked in that order on a surface of a supportbody that includes the fuel gas path. Note that oxygen-containing gasflows between the fuel cells 32.

Further, in the fuel cell device of the present embodiment, the fuelcells 32 may be solid oxide fuel cells, and flat plate shaped orcylindrical shaped, for example. In addition, the shape of the housing34 may also be changed as appropriate.

Moreover, the reformer 3 illustrated in FIG. 3 reforms a raw fuel suchas natural gas or kerosene supplied via a raw fuel supply pipe 39 toproduce a fuel gas. It is preferable that the reformer 3 be capable ofperforming steam reforming which has an efficient reforming reaction.The reformer 3 includes a vaporizing unit 36 that vaporizes water and areforming unit 37 that has a reforming catalyst (not illustrated) forreforming the raw fuel into fuel gas disposed therein. Then, the fuelgas produced in the reformer 3 is supplied to the manifold 33 via a fuelgas leading-out pipe 38. The fuel gas is then supplied via the manifold33 to the fuel gas paths formed inside the fuel cells 32.

Moreover, FIG. 3 illustrates the cell stack device 40 housed in thehousing 34, with the cell stack device 40 removed rearward and a portionof the housing 34 (front and back surfaces) removed. Here, in the module1 illustrated in FIG. 3, the cell stack device 40 can be slid and housedin the housing 34.

Note that an oxygen-containing gas leading-in member 35 is disposed inthe interior of the housing 34, between the cell stacks 2 arranged sideby side on the manifold 33, so that the oxygen-containing gas flowsalong the sides of the fuel cells 32, from a lower end portion toward anupper end portion.

As illustrated in FIG. 4, the housing 34 of the module 1 has a two-layerstructure that includes an inner wall 41 and an outer wall 42. The outerwall 42 forms the outer frame of the housing 34, and the inner wall 41forms a power generation chamber 43 that houses the cell stack device40. Furthermore, in the housing 34, the space between the inner wall 41and the outer wall 42 forms an oxygen-containing gas flow path 44through which oxygen-containing gas flows toward the fuel cells 32.

Here, the oxygen-containing gas leading-in member 35 is inserted from anupper portion of the housing 34, passing through the inner wall 41, andfixed. The oxygen-containing gas leading-in member 35 includes, on anupper side, an oxygen-containing gas inflow opening (not illustrated)through which the oxygen-containing gas flows, and flanges 45; and, on alower side, an oxygen-containing gas outflow opening 46 through whichthe oxygen-containing gas flows toward a lower end portion of each ofthe fuel cells 32. Moreover, a thermal insulating member 47 is arrangedbetween each flange 45 and the inner wall 41.

Note that while the oxygen-containing gas leading-in member 35 isdisposed so as to be positioned between the two cell stacks 2 arrangedside by side in the interior of the housing 34 in the FIG. 4, the numberof the cell stacks 2 may be changed as appropriate. For example, whenthe housing 34 houses only one cell stack 2, two oxygen-containing gasleading-in members 35 may be provided and disposed so as to sandwich thecell stack 2 from both side surface sides.

Moreover, the thermal insulating members 47 may also be formed insidethe power generation chamber 43 as appropriate in order to maintain ahigh temperature inside the module 1, which prevents a decrease in thetemperature of the fuel cells 32 (cell stacks 2) and a decrease in poweroutput that result from excessive radiation of heat from the inside ofthe module 1.

It is preferable that the insulating members 47 be arranged in thevicinity of the cell stacks 2. It is particularly preferable that theinsulating members 47 be arranged on the side surfaces of the cellstacks 2 extending in the direction in which the fuel cells 32 arearranged and that the insulating members 47 have a width greater than orequal to the width of the side surfaces of the cell stacks 2 in thedirection in which the fuel cells 32 are arranged. It is preferable thatthe thermal insulating members 47 be arranged on both side surface sidesof the cell stacks 2. This makes it possible to effectively inhibittemperature decreases in the cell stacks 2. Furthermore, this makes itpossible to inhibit oxygen-containing gas led in by theoxygen-containing gas leading-in member 35 from being discharged fromthe side surface sides of the cell stacks 2, thereby making it possibleto promote the flow of oxygen-containing gas between the fuel cells 32of the cell stacks 2. Note that openings 48 are formed in the thermalinsulating members 47 arranged on both side surface sides of the cellstacks 2 in order to regulate the flow of oxygen-containing gas to thefuel cells 32 and to decrease the differences in temperature in thelengthwise direction in which the fuel stacks 2 extend as well as in thedirection in which the fuel cells 32 are stacked.

Moreover, on the inner sides of the inner walls 41 extending in thedirection in which the fuel cells 32 are arranged, exhaust gas innerwalls 49 are formed. The space between the inner walls 41 and theexhaust gas inner walls 49 forms exhaust gas flow paths 50 that allowthe exhaust gas inside the power generation chamber 43 to flow from topto bottom. Furthermore, the exhaust gas flow paths 50 are communicatedto an exhaust hole 51 formed at the bottom of the housing 34. Further,the thermal insulating members 47 are provided on the cell stack 2 sideof the exhaust gas inner walls 49 as well.

Accordingly, exhaust gases produced when the module 1 operates (during astartup process, power generation, or a shutdown process) flow throughthe exhaust gas discharge paths 50 and then are discharged through theexhaust hole 51. Note that the exhaust hole 51 may be formed by cuttingout a portion of the bottom of the housing 34 or by using a pipe-shapedmember.

Note that, inside the oxygen-containing gas leading-in member 35, athermocouple 52 for measuring the temperature near the cell stacks 2 isformed such that a temperature sensing portion 53 of the thermocouple 52is positioned at the center of the fuel cells 32 in the lengthwisedirection and at the center in the direction in which the fuel cells 32are arranged.

Further, in the module 1 configured as described above, at least aportion of the fuel gas and the oxygen-containing gas discharged fromthe fuel gas flow paths of the fuel cells 32 and not used in powergeneration is combusted between an upper end portion side of the fuelcells 32 and the reformers 3, making it possible to increase andmaintain the temperature of the fuel cells 32. In addition, this makesit possible to heat the reformers 3 disposed above each of the fuelcells 32 (cell stacks 2), and efficiently perform a reformation reactionin the reformers 3. Furthermore, during normal power generation, themodule 1 has a temperature of 500 to 800° C. due to the abovementionedcombustion process and the generation of power in the fuel cells 32.Therefore, the exhaust gas discharged from the module 1 also becomeextremely high in temperature.

FIGS. 5 and 6 are configuration diagrams illustrating yet other examplesof the configuration of the cooling and heating device of the presentembodiment. FIG. 5 illustrates the cooling function, FIG. 6 illustratesthe heating function, and the configuration of each device is the same.Thus, in the following descriptions of the configurations, FIG. 5 willbe mainly used for explanation.

The cooling and heating devices illustrated in FIGS. 5 and 6, comparedto the cooling and heating devices illustrated in FIGS. 1 and 2, differin that each use water as the first fluid, and include a hot waterstorage unit including a hot water storage tank 54 for storing hot waterheated and produced by the heat exchanger 6.

In the cooling and heating devices illustrated in FIG. 1 and FIG. 2,there is still room for improving the effective utilization of the heatof the exhaust gas discharged from the module 1, particularly when thecooling and heating switch has been turned off by user settings orautomatic operation, and when the cooling and heating functions are inexcess.

Here, in each of the cooling and heating devices illustrated in FIGS. 5and 6, the hot water storage unit is provided, allowing hot water to beproduced using the heat of the exhaust gas discharged from the module 1and not used in cooling and heating. This hot water is thus provided asa hot water supply, making it possible to achieve a cooling and heatingdevice having increased overall efficiency.

Here, the storage tank 54 includes water inflow piping 56 having one endconnected to the first piping 30 via a third switching unit 55 and theother end connected to the hot water storage tank 54, and water outflowpiping 58 having one end connected to the storage tank 54 and the otherend connected to the first piping 30 via a fourth switching unit 57.Note that a pump 59 is provided between the heat exchanger 6 and thefourth switching unit in the first piping 30, and the hot water storagetank 54 includes a stored water volume sensor and a stored watertemperature sensor for measuring the temperature and volume of the hotwater stored in the hot water storage tank 54. These sensors arecollectively referred to as hot water storage tank sensor 60 in thedescriptions below.

For example, the following control is preferably performed to furtherimprove overall efficiency in cases such as when the first fluid is notflowing through the circulation piping 26, when the operation of thepump 31 satisfies a predetermined condition (operation shutdowncontinuing for at least one hour, for example) to activate the pump 31so that the temperature measured by the temperature sensor 29 providedin the cooling/heating target area reaches a predetermined temperaturerange (a temperature of at least 10° C. and less than 25° C., forexample), and when the temperature and the volume of the hot watermeasured by the hot water storage tank sensor 60 are less than or equalto predetermined ranges.

For example, the following describes the control performed on the basisof the temperature and the volume of the hot water measured by the hotwater storage tank sensor 60. First, the controller 13 determines if thetemperature and volume of the hot water in the hot water storage tanktransmitted by the hot water storage tank sensor 60 are within thepredetermined ranges. When the temperature and volume are within thepredetermined ranges, the controller 13 continues the control performedup to that time.

When the temperature and volume are outside the predetermined ranges,the controller 13 controls the exhaust gas switching unit 25 so that atleast a portion of the exhaust gas discharged from the module 1 flowsinto the heat exchanger 6. Then, the controller 13 controls the thirdswitching unit 55 so that at least a portion of the hot water producedby the heat exchanger 6 flows to the water inflow piping 56, andcontrols the fourth switching unit 57 so that the water in the hot waterstorage tank 54 flows into the heat exchanger 6 via the water outflowpiping 58.

Note that, when the control performed before this control requires theheating function, the controller 13 may control the third switching unit55 and the fourth switching unit 57 so that a portion of the water thatflows through the first piping 30 flows through the water inflow piping56 and the water outflow piping 58. On the other hand, when the controlperformed before this control requires the cooling function, thecontroller 13 may control the third switching unit 55 and the fourthswitching unit 57 so that all of the water flows through the waterinflow piping 56 and the water outflow piping 58. The controller 13, inaddition to this control, controls the exhaust gas switching unit 25 sothat all or a portion of the exhaust gas discharged from the module 1flow into the heat exchanger 6.

Specifically, when the temperature and the volume of the hot water inthe hot water storage tank transmitted by the hot water storage tanksensor 60 are outside the predetermined ranges, and the temperature ofoutside air or the temperature of the cooling/heating target areasatisfies the first condition (a temperature of at least 25° C.continuously for at least one hour, for example), the controller 13 maycontrol the exhaust gas switching unit 25 so that the exhaust gasdischarged from the module 1 is supplied into both the heat exchanger 6and the thermoacoustic cooler 14. Further, when the temperature ofoutside air or the temperature of the cooling/heating target areasatisfies the second condition (a temperature of less than 10° C.continuously for at least one hour, for example), the controller 13 maycontrol the exhaust gas switching unit 25 so that the exhaust gasdischarged from the module 1 is supplied only to the heat exchanger 6.

With such a configuration, the cooling and heating device furtherincludes a hot water supply function in addition to the cooling andheating function, making it possible to achieve a cooling and heatingdevice having increased overall efficiency.

Note that, in the above, when the first fluid is not flowing through thecirculation piping 26, and when the operation of the pump 31 satisfies apredetermined condition (operation shutdown continuing for at least onehour, for example) to activate the pump 31 so that the temperaturemeasured by the temperature sensor 29 provided in the cooling/heatingtarget area reaches a predetermined temperature range (a temperature ofat least 10° C. and less than 25° C., for example) as well, thecontroller 13 performs control similar to that described above, makingit possible to achieve a cooling and heating device control havingincreased overall efficiency.

The present invention has been described in detail above. However, thepresent invention is not limited to the embodiments described above, andvarious modifications or improvements can be made without departing fromthe spirit of the present invention.

For example, while the aforementioned hybrid system has been describedusing a fuel cell device that includes solid oxide fuel cells as anexample of the fuel cell device, the fuel cell device may be a solidhigh polymer fuel cell device, for example. When a solid high polymerfuel cell device is used, the heat produced in the reformation reaction,for example, may be effectively utilized, and the configuration may bechanged as appropriate.

REFERENCE SIGNS LIST

-   1 Fuel cell module-   6 Heat exchanger-   14 Thermoacoustic cooler-   24 Second piping-   25 Exhaust gas switching unit-   26 Circulation piping-   27 First switching unit-   28 Second switching unit-   29 Temperature sensor-   30 First piping-   54 Hot water storage tank-   55 Third switching unit-   56 Water inflow piping-   57 Fourth switching unit-   58 Water outflow piping-   60 Hot water storage tank sensor

1. A cooling and heating device comprising: a fuel cell devicecomprising a fuel cell; a heating unit configured to utilize heat of anexhaust gas discharged from the fuel cell; a thermoacoustic coolercomprising a cooling unit which is configured to perform a coolingfunction with use of the heat of the exhaust gas discharged from thefuel cell; and an exhaust gas switching unit that allows the exhaust gasdischarged to flow from the fuel cell to at least one of thethermoacoustic cooler and the heating unit.
 2. The device according toclaim 1, wherein the heating unit comprises a heat exchanger thatexchanges heat between the exhaust gas discharged from the fuel cell anda first fluid.
 3. The device according to claim 2, further comprising: afirst piping connected to the heat exchanger, and configured to flow afirst fluid; and a second piping provided on a periphery of the coolingunit, and configured to flow a second fluid; wherein the exhaust gasswitching unit flows one of the first fluid and the second fluid to acooling/heating target area.
 4. The device according to claim 3, furthercomprising: circulation piping provided in the cooling/heating targetarea, wherein one end of the first piping and one end of the secondpiping are connected to the circulation piping via a first switchingunit, and an other end of the first piping and an other end of thesecond piping are connected to the circulation piping via a secondswitching unit.
 5. The device according to claim 4, further comprising:a controller that controls the first switching unit and the secondswitching unit, wherein the controller controls the first switching unitand the second switching unit to allow one of the first fluid and thesecond fluid to flow through the circulation piping on the basis of apredetermined condition.
 6. The device according to claim 5, furthercomprising: a temperature sensor that measures one of a firsttemperature related to an outside air and a second temperature relatedto the cooling/heating target area, the predetermined condition includesa first condition related to a measurement of the first temperature orthe second temperature, wherein the controller controls the firstswitching unit and the second switching unit to allow the second fluidto flow through the circulation piping when the measurement by thetemperature sensor satisfies the first condition.
 7. The deviceaccording to claim 5, further comprising: a temperature sensor thatmeasures one of a first temperature related to an outside air and asecond temperature related to the cooling/heating target area, thepredetermined condition includes the second condition related to ameasurement of the first temperature or the second temperature, whereinthe controller controls the first switching unit and the secondswitching unit to allow the first fluid to flow through the circulationpiping when the measurement satisfies the second condition.
 8. Thedevice according to claim 6, wherein the controller controls the exhaustgas switching unit to allow the exhaust gas discharged from the fuelcell to flow into the thermoacoustic cooler when the second fluid flowsthrough the circulation piping.
 9. The device according to claim 7,wherein the controller controls the exhaust gas switching unit to allowthe exhaust gas discharged from the fuel cell to flow into the heatexchanger when the first fluid flows through the circulation piping. 10.The device according to claim 3, further comprising: a hot water storagetank; a third switching unit and a forth switching unit, connected tothe heat exchanger a water inflow piping comprising one end connected tothe first piping via the third switching unit, and an other endconnected to the hot water storage tank; and a water outflow pipingcomprising one end connected to the hot water storage tank and an otherend connected to the first piping via the fourth switching unit.
 11. Thedevice according to claim 10, wherein the hot water storage tank furthercomprises one of a stored water volume sensor and a stored water tanktemperature sensor, and the controller controls the exhaust gasswitching unit to allow the exhaust gas discharged from the fuel cell toflow into the heating unit or into the heating unit and thethermoacoustic cooler on the basis of a value measured by one of thestored water volume sensor and the stored water temperature sensor. 12.The device according to claim 11, wherein the controller controls thethird switching unit and the fourth switching unit on the basis of avalue measured by one of the stored water volume sensor and the storedwater temperature sensor.
 13. The device according to claim 6, furthercomprising: a hot water storage tank; a water inflow piping comprisingone end connected to the first piping via a third switching unit, and another end connected to the hot water storage tank; and a water outflowpiping comprising one end connected to the hot water storage tank and another end connected to the first piping via a fourth switching unit. 14.The device according to claim 7, further comprising: a hot water storagetank; a water inflow piping comprising one end connected to the firstpiping via a third switching unit, and an other end connected to the hotwater storage tank; and a water outflow piping comprising one endconnected to the hot water storage tank and an other end connected tothe first piping via a fourth switching unit.
 15. The device accordingto claim 13, wherein the controller controls the third switching unitand the fourth switching unit on the basis of a value measured by one ofthe stored water volume sensor and the stored water temperature sensor.16. The device according to claim 14, wherein the controller controlsthe third switching unit and the fourth switching unit on the basis of avalue measured by one of the stored water volume sensor and the storedwater temperature sensor.